Time Sert 5761E Big Sert kit, made by Time Sert in the USA. Big Sert means it's "oversized" for use when a Helicoil or a competitive brand has failed. The 5761E is used in cast iron chevy big blocks after a Heli Coil has maded the hole bigger. It has a larger outside diameter but still accepts the original size 7/16-14 head bolts. If doing a first time repair the oversize kit is not needed, we recommend using the Time Sert 0761D. 

• Core Drill Bit (Reamer) 37/64"
• Counterbore (with pilot assembly) The counter-bore tool is needed to allow the inserts to sit flush as to not interfere with the cylinder head.
• Tap - 7/16 Big Sert 
• Tap Guide pn 57655 - for guiding the tooling straight.
• Installation Driver - for installing insert by cold rolling threads and expanding the bottom locking it into place.
• Includes 5 Inserts .60" length pn 57611- Big Sert inserts have a larger O.D.
• Loctite 266 - Permanent high temperature red loctite.

*Time Sert is the only GM approved method for repairing head bolt threads.